1. Field of the Invention
The present invention relates to gas analyzers. More specifically, the present invention is directed to a gas analyzer for determining the BTU or calorific content of a combustible gas.
2. Description of the Prior Art
The measurement of BTU or caloric content of a combustible gas such as that supplied for home heating, etc., provides a measure of the quality of the gas being supplied and, hence, the appropriate rate or cost for the gas can be billed to a customer who formerly was charged a rate based simply on cubic volume of gas consumption. Conventional gas analyzers for determining the composition of an unknown gas are well-known in the art. The basic analyzer is known as the Orsat type and is used to absorb the constituent gases one at a time from a gas mixture and to determine the constituent quantities from the resulting decreases in the gas pressure. The resulting gas analysis could be used as a basis for customer billing. However, such an apparatus is wholly inpractical for mass installation in gas consumer locations. Another prior art gas analyzer is based on the use of the thermal conductivity of the unknown gas which gas is analyzed by comparing its rate of thermal conductivity with that of a standard reference gas. Another prior art gas analyzing device used, in various arrangements, a catalyzing wire which has its temperature affected by a gas being burned adjacent to the wire to produce an output signal which is used to ascertain the percentage of combustible gas in the gas being tested. Still another group of prior art gas analyzers were based on an optical analysis of the color, etc. of a gas flame to provide a measure of combustible gas content. All of these prior art devices have serious shortcomings in providing a rapid and accurate measure of the BTU content of the combustible gas while utilizing a compact and simple structure suitable for mass production and capable of being mounted in unattended customer locations. Accordingly, it is desirable to provide a BTU meter capable of determining the BTU or caloric content of an unknown gas composition to provide a measure of the billing cost to be assigned to the gas during a sale of the gas to a consumer.